Wound Care: Pulling Out All The Stops

Early one evening in mid December, a mare normally first to the feed bucket didn’t come up from the field with the rest of the band. She arrived a few minutes later, looking dazed, walking past her feed bucket to stand head down along a wall. As her caretaker approached, she saw a horizontal gash running from just behind and above the mare’s elbow through the entire length of her chest wall and extending into the mare’s flank.

The cut was so deep the ribs were exposed. The skin was hanging down off her in a gigantic flap, the length of the horizontal gash being about 36 inches with the sides of the flap at least 14 inches long. To make matters worse, the mare had a winter coat and had obviously been rolling in the mud earlier in the day.

The exact cause of the wound remains unknown, although the wound’s relatively clean, straight cut and depth lead veterinarians to suspect foul play.

The exposed tissue itself was free of obvious contamination, so the two vets called in decided not to trim back hair from the edge of the wound or try to clean her side. The risk of contaminating the wound with hair or dirt was considered too great.

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With the mare heavily sedated but standing, two vets worked simultaneously, taking 2.5 hours to suture the wound. The closure was done in three layers and took a conservative estimate of 150 separate sutures, over 80 of those in the skin.

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After some discussion, the pregnant mare was put on 70 cc/day of procaine penicillin G and 24 cc/day of gentamicin, both intramuscular, split dose. Controlling infection was critical. Even without infection, it was likely some skin would be lost since the wound had not bled much and the blood supply to the area had pretty much been severed.

First HoursThe first 24 to 36 hours were rocky. The mare was depressed, not eating well and stood keeping her body curved around to protect the injured side and relieve tension on the suture line. She was given phenylbutazone the night of the injury and was started on the second day on Phyto-Quench (Uckele, www.uckele.com 800/248-0330), an herbal anti-inflammatory/antioxidant/anticoagulant.

By the third day she was brighter, eating well, standing normally and even trotted around a bit. The penicillin and gentamicin seemed to be working. There was no drainage from the suture line and only a hint of fluid collection under the skin. She had extensive collections of edema fluid along her belly below the level of the wound. However, this was expected because of the damaged circulation. Her condition overall was almost too good to be true — and it was.

Immediately after receiving a penicillin injection on the third day, the mare had a severe reaction (see March 2002), throwing herself to the ground and thrashing violently. After about five minutes she got up but was still obviously shaken. Fortunately, she popped only a few skin sutures, but it was feared she had probably torn quite a bit of the deeper repair. The next day, the flap showed small fluid pouches under the skin and the suture line was oozing.

Over the next few days, the skin under the suture line began to feel “leathery.” The fluid pouches enlarged and the pressure on these produced some pus at the suture line. The mare had been put on Bactrim after the penicillin was stopped but either this was not enough or the infection was simply inevitable.

The two worst pockets of infection were opened for drainage and twice-daily flushings. By the eighth day, the skin in the back portion of the flap had split open at the junction between viable and dead skin, in a line running parallel with the original gash but about two inches below it. With these pockets of infection and the large area of newly opened tissue, complete healing was estimated at another six to 10 weeks, which would be as late as mid March.

Treatment OptionsAbout the only good thing to come from this, beyond saving the mare, was the opportunity to field test medications and wound flushes.

Dr. Eleanor Kellon, one of the vets on this case, experimented with a variety of flushing solutions, including plain sterile saline, plain sterile water, sterile water or saline with antibiotics included, sterile water with either 10% or 0.25% peroxide. Each was tried for three to four days.

By far the best results were obtained with the 0.25% peroxide in distilled water. The other solutions would get the pockets flushed well, but they would always start draining pus again before the next flush 12 hours later. The infection wasn’t worse, but it wasn’t improving either. The 10% peroxide solution left less pus between flushes but no healing. When the switch was made to 0.25% peroxide, the response was rapid and obvious.

We also substituted distilled water for the sterile water after the initial three days and the response continued to be excellent, with no detectable difference between sterile or distilled water, which is much cheaper.

Since bandaging was not an option, we first tried treating the areas between cleanings/flushings with a nitrofurazone spray. However, this seemed to irritate the area that had opened when the skin split and healing was slow. The granulating bed was also getting a red, cobblestone-like appearance and was slightly raised.

The last thing we wanted was excess granulation tissue (proud flesh), so we switched to DermaGel (Equine America, www.equine-america.com, 800/838-7524). This reduced the redness and resulted in a growth of skin, visible as a 1/16” wide advancing edge around the perimeter.

However, the cobblestone appearance remained, so we switched to CothiVet (Neogen Corporation, www.neogen.com, 800/525-2022). The CothiVet was effective in quieting down the granulation reaction, keeping the tissue smooth and level with the skin, although the skin healing didn’t appear to be as rapid as with the Derma Gel. Both products did an excellent job of keeping the granulating surfaces clean and pink.

By mid January, all the sutures were removed. They were left in this long as a sort of natural bandage to keep the skin in place, but they were getting irritated. The vet also removed all the dead skin and started what was to make the biggest difference in healing — laser treatments.

For laser treatment of the wound we used the Respond 2400 XL Laser System (203/481-2810), Ultra Wide head, 904 nm wavelength, slowly sweeping over the entire granulating bed, delivering a dose of approximately 4 Joules to each one-inch area. This was done daily for the first three days, then every other day.

The laser increased the skin growth and by early February — nearly a month earlier than expected — the open area was closed except for a narrow band of granulation. The mare was released back to her herd. Unfortunately, she later aborted her foal. However, she remains healthy and was rebred this spring.

Bottom LineFor a severe-wound flush, we found 0.25% peroxide in sterile water the most effective choice. This is 2.5 cc of peroxide per liter distilled water.

For wound medications, CothiVet was the most effective topical treatment when granulation tissue seemed to be forming proud flesh or was getting higher than the level of surrounding skin. Otherwise, we would use Derma Gel for more rapid skin healing/coverage as well as more analgesia/wound soothing. Both products are available through your veterinarian. Laser therapy and Phyto-Quench were excellent supportive therapies.